120 lines
4.3 KiB
Markdown
120 lines
4.3 KiB
Markdown
---
|
|
layout: "docs"
|
|
page_title: "Configuring Terraform Settings"
|
|
sidebar_current: "docs-config-terraform"
|
|
description: |-
|
|
The "terraform" configuration section is used to configure some behaviors
|
|
of Terraform itself.
|
|
---
|
|
|
|
# Terraform Settings
|
|
|
|
The special `terraform` configuration block type is used to configure some
|
|
behaviors of Terraform itself, such as requiring a minimum Terraform version to
|
|
apply your configuration.
|
|
|
|
## Terraform Block Syntax
|
|
|
|
Terraform-specific settings are gathered together into `terraform` blocks:
|
|
|
|
```hcl
|
|
terraform {
|
|
# ...
|
|
}
|
|
```
|
|
|
|
Each `terraform` block can contain a number of settings related to Terraform's
|
|
behavior. Within a `terraform` block, only constant values can be used;
|
|
arguments may not refer to named objects such as resources, input variables,
|
|
etc, and may not use any of the Terraform language built-in functions.
|
|
|
|
The various options supported within a `terraform` block are described in the
|
|
following sections.
|
|
|
|
## Configuring a Terraform Backend
|
|
|
|
The selected _backend_ for a Terraform configuration defines exactly where
|
|
and how operations are performed, where [state](/docs/state/index.html) is
|
|
stored, etc. Most non-trivial Terraform configurations will have a backend
|
|
configuration that configures a remote backend to allow collaboration within
|
|
a team.
|
|
|
|
A backend configuration is given in a nested `backend` block within a
|
|
`terraform` block:
|
|
|
|
```hcl
|
|
terraform {
|
|
backend "s3" {
|
|
# (backend-specific settings...)
|
|
}
|
|
}
|
|
```
|
|
|
|
More information on backend configuration can be found in
|
|
[the _Backends_ section](/docs/backends/index.html).
|
|
|
|
## Specifying a Required Terraform Version
|
|
|
|
The `required_version` setting can be used to constrain which versions of
|
|
the Terraform CLI can be used with your configuration. If the running version of
|
|
Terraform doesn't match the constraints specified, Terraform will produce
|
|
an error and exit without taking any further actions.
|
|
|
|
When you use [child modules](./modules.html), each module
|
|
can specify its own version requirements. The requirements of all modules
|
|
in the tree must be satisfied.
|
|
|
|
Use Terraform version constraints in a collaborative environment to
|
|
ensure that everyone is using a spceific Terraform version, or using at least
|
|
a minimum Terraform version that has behavior expected by the configuration.
|
|
|
|
The `required_version` setting applies only to the version of Terraform CLI.
|
|
Various behaviors of Terraform are actually implemented by Terraform Providers,
|
|
which are released on a cycle independent of Terraform CLI and of each other.
|
|
Use [provider version constraints](./providers.html#provider-versions)
|
|
to make similar constraints on which provider versions may be used.
|
|
|
|
The value for `required_version` is a string containing a comma-separated
|
|
list of constraints. Each constraint is an operator followed by a version
|
|
number, such as `> 0.12.0`. The following constraint operators are allowed:
|
|
|
|
* `=` (or no operator): exact version equality
|
|
|
|
* `!=`: version not equal
|
|
|
|
* `>`, `>=`, `<`, `<=`: version comparison, where "greater than" is a larger
|
|
version number
|
|
|
|
* `~>`: pessimistic constraint operator, constraining both the oldest and
|
|
newest version allowed. For example, `~> 0.9` is equivalent to
|
|
`>= 0.9, < 1.0`, and `~> 0.8.4`, is equivalent to `>= 0.8.4, < 0.9`
|
|
|
|
Re-usable modules should constrain only the minimum allowed version, such
|
|
as `>= 0.12.0`. This specifies the earliest version that the module is
|
|
compatible with while leaving the user of the module flexibility to upgrade
|
|
to newer versions of Terraform without altering the module.
|
|
|
|
## Specifying Required Provider Versions
|
|
|
|
The `required_providers` setting is a map specifying a version constraint for
|
|
each provider required by your configuration.
|
|
|
|
This is one of several ways to define
|
|
[provider version constraints](./providers.html#provider-versions),
|
|
and is particularly suited to re-usable modules that expect a provider
|
|
configuration to be provided by their caller but still need to impose a
|
|
minimum version for that provider.
|
|
|
|
```hcl
|
|
terraform {
|
|
required_providers = {
|
|
aws = ">= 1.0.0"
|
|
}
|
|
}
|
|
```
|
|
|
|
Re-usable modules should constrain only the minimum allowed version, such
|
|
as `>= 1.0.0`. This specifies the earliest version that the module is
|
|
compatible with while leaving the user of the module flexibility to upgrade
|
|
to newer versions of the provider without altering the module.
|